Starter for an alcohol engine

ABSTRACT

A starter for an alcohol engine, which incorporates a reformer containing catalyst heated by exhaust gas to thereby react fuel alcohol so as to produce reformed gas containing hydrogen and carbon monoxide as main components and to store the produced gas in the reformer. The reformed gas is supplied to a carburetor of the engine at its starting time to mix it with the main fuel alcohol to supply the mixture to a combustion chamber so as to facilitate easy ignition.

TECHNICAL FIELD

The present invention relates to a starter for an engine using alcohol,such as methanol, ethanol or the like, as its fuel.

BACKGROUND ART

In the recent years, alcohol has been considered as a prospectivesubstitute for gasoline as fuel for automotive vehicles. However,alcohol has a higher boiling point than gasoline, as for example 64.5°C. in methanol. Consequently, a problem has developed in starting analcohol fueled engine.

Accordingly, several proposals for solving the starting problems havebeen suggested. One such proposal is to store gasoline as an auxiliaryfuel besides the alcohol and to use the gasoline at the starting timeand to switch to alcohol after a certain warm up driving time i.e. whenthe temperature rises up to an extent sufficient for easy evaporation ofthe alcohol. Another proposal is to evaporate the alcohol by warming upthe manifold by an electric heating wire at the starting time.

However, the former proposal has the disadvantage that the auxiliaryfuel should be carried separately from the gasoline and the latterproposal has the disadvantage that a longer time is required forstarting.

DISCLOSURE OF INVENTION

In view of the aforementioned situation, the present invention has asits object to provide a starter for an alcohol engine which is able tostart an alcohol engine as easily as a conventional gasoline engine.

In accordance with the above object, in the present invention, a part ofthe fuel alcohol is reformed into a gaseous fuel containing hydrogen andcarbon monoxide as the main components during operation of the engineand is stored and thus stored gaseous fuel is supplied to the enginewhen starting the engine so as to obtain an easy ignition thereof.

The invention will now be explained by referring to the drawings.

BRIEF EXPLANATION OF DRAWING

FIG. 1 is a diagrammatic illustration showing one embodiment of thepresent invention; and

FIG. 2 is a cross-sectional view showing an essential part of a modifiedembodiment thereof.

BEST MODE OF CARRYING OUT THE INVENTION

In FIG. 1, 1 is an air cleaner, 2 is a carburetor, 3 is an intake tube,4 is a combustion chamber of the engine body, 5 is an exhaust tube, and6 is a fuel tank for storing the fuel alcohol. The alcohol is suppliedto the carburetor 2 via a main fuel passageway 7.

As the starter according to the present invention, a passageway 8leading from the fuel tank 6 to the carburetor 2 is provided separatelyfrom the main fuel passageway 7. In this passageway 8, anelectromagnetic valve 9, an evaporator 10, an electromagnetic valve 11,a reformer 12, and an electromagnetic valve 13 are inserted in the aboveorder starting from the fuel tank side. A passageway 14 branched fromthe exhaust tube 5 at comparatively upstream point thereof is providedvia an insertion of an electromagnetic valve 15. Passageway 14 extendsto the reformer 12 and to the evaporator 10 in such a manner that thesecomponents are supplied with heat from the exhaust gas. This passageway14 is thereafter connected at relatively downstream position of theexhaust tube 5 via an intervention of an electromagnetic valve 16. Theaforementioned reformer 12 has a catalyst bed which is filled up with areforming catalyst at the inside.

17 and 18 are sensors for detecting the pressure and the temperature,respectively, in the reformer 12, 19 is a sensor for exhaust gastemperature, and 20 is a control unit operating by signals sent fromthese sensors 17, 18 and 19 and a signal sent from a starter switch 21and for controlling the electromagnetic valves 9, 11, 13, 15 and 16.

This control unit 20 acts to open the electromagnetic valves 9, 11, 15and 16 when the pressure in the reformer 12 detected by the pressuresensor 17 is lower than a previously settled value (this settled valueis compensated by a temperature detecting signal sent from thetemperature sensor 18) and also when the exhaust gas temperaturedetected by an exhaust gas temperature sensor 19 is higher than apreviously settled value and it also acts to open the electromagneticvalve 13 when the starter switch 21 is turned on.

The operation of the device of the present invention will be explainedhereinafter.

During the operation of the engine, if the pressure of the reformed gasin the reformer 12, which has been produced and stored therein in amanner described hereinafter, is lower than the previously settledvalue, namely if the residual amount of the reformed gas is notsufficient, the electromagnetic valves 9, 11, 15 and 16 are openedprovided that the exhaust gas temperature is higher than the previouslysettled value, namely when the exhaust gas temperature is high enoughfor the formation of the reformed gas, then the alcohol delivered fromthe fuel tank 6 to the reformer 12 via the evaporator 10 reacts on thecatalyst bed (in case of methanol; CH₃ OH→2H₂ +CO) and the reformed gascontaining hydrogen and carbon monoxide as the main components isproduced. Herein, this reaction is an endothermic reaction and thereaction heat is obtained from the exhaust gas passing through thepassageway 14. The produced reformed gas is adsorbed in the reformingcatalyst in the reformer 12 since the electromagnetic valve 13 is thenclosed. If the pressure in the reformer 12 rises by this, theelectromagnetic valves 9, 11, 15, and 16 are closed again to discontinuefurther production of the reformed gas and the already produced reformedgas remains stored in the reformer 12.

At restarting of the engine after it had been stopped, the starterswitch 21 is operated to be in the ON condition, and by this theelectromagnetic valve 13 is opened, and as has been explained in theforegoing, the stored reformed gas in the reformer 12 being rich inhydrogen and carbon monoxide is supplied to the carburetor 2 and thisreformed gas is mixed with the air and with alcohol fed through the mainfuel passageway 7 in the carburetor 2 and is fed to the combustionchamber 4. This reformed gas has very excellent combustioncharacteristics of a high combustion speed, and of small ignitionenergy. Accordingly, the engine can be started very easily.

Once the engine is started, it can be driven only by alcohol so that theelectromagnetic valve 13 is closed again simultaneously with the turnoff of the starter switch 21 and the supply of the reformed gas isdiscontinued.

After the supply of the reformed gas, if there still remains asufficient reformed gas in the reformer 12, the formation of thereformed gas is not effected even if the exhaust gas temperature ishigh, however, if there is not much reformed gas remaining therein, theelectromagnetic valves 9, 11, 15 and 16 are kept opened at rising of theexhaust gas temperature and the reformed gas is produced and stored inthe same manner as has been explained in the foregoing to prepare forthe next starting.

In case sufficient heat for the reformation reaction is not obtainedfrom the heat of the exhaust gas, an electric heating wire 22 isembedded in the reformer 12 and an electric current is suppliedsubstantially synchronized with the opening of the electromagneticvalves 9, 11, 15 and 16 and the necessary heat for the reformationreaction may be produced for a part or all by this electric heat.

Furthermore, the reformer 12 may be one incorporating evaporator 10 andin this case the electromagnetic valve 11 can be dispensed with.

FIG. 2 shows an embodiment in which the reformer for reforming alcoholinto gas and a storage device for storing the reformed gas are providedseparately.

Namely, a cylindrical shaped reformer 31 is arranged in the exhaust gaspipe 5 and a cooling tube 32 penetrating the exhaust gas pipe 5 andconnected at one end of the reformer 31 is arranged outside the exhaustgas pipe 5. A supply conduit 33 of alcohol is introduced in the coolingtube 32 at middle point thereof and extended coaxially therein and alsocoaxially in the reformer 31 to form double tube construction and an endthereof is opened adjacent another end of the reformer 31. Inside thereformer 31, the reforming catalyst is filled up.

The aforementioned cooling tube 32 is connected via a non-return valve35 to a lower end portion of a gas storage device 36 formedcylindrically, which is filled up with adsorbing member 37 such asactivated carbon, alumina, metal hydride or the like. An upper end ofthe gas storage device 36, a normally closing valve 38 (acting in thesame manner with the aforementioned electromagnetic valve 13) ismounted. 39 is a gas outlet.

The operation is now explained. During operation of the engine, alcoholis supplied via the alcohol supply conduit 33 into the reformer 31 andis evaporated in the conduit 33 by a heat exchange with the reformed gaspassing through the cooling tube 32 for instance, and this alcohol isreformed into gas such as hydrogen and carbon monoxide or the like inthe reformer 31 by the reforming catalyst 34 while taking the heat ofthe exhaust gas flowing through the exhaust tube 5. The reformed gaspasses through the cooling tube 32 and is cooled by the heat exchangewith the alcohol flowing through the supply conduit 33 prior to itsreaction and enters into the gas storage device 36 via the non-returnvalve 35 and stored therein by adsorption of the adsorbing member 37.The gas storage device 36 may be a mere hollow bomb without theadsorbing member 37 but the storage efficiency can be much improved byfilling up the adsorbing member 37.

After stopping the engine, even if the pressure in the reformer 31decreases, the reformed gas remains stored in the storage device 36since the non-return valve 35 is provided at entrance of the storagedevice 36. At starting of the engine, the control valve 38 is opened andthe gas stored in the gas storage device 36 is supplied to thecarburetor of the engine through the gas outlet 39 and via a tubingsystem not shown in the drawing.

By providing the reformer and the gas storage device separately asexplained above, the following advantage can be obtained. Firstly, sincethe reformer is exposed to the exhaust gas of the engine, it may beheated up to 300° to 700° C. during operation of the engine so that ifthe gas is stored in such a high temperature reformer, it is inevitablethat the amount of storage decreases. However, if the gas storage deviceis provided separately, the amount of storage can substantially beincreased since the gas can be stored at a lower temperature. Secondly,if the gas is stored in the reformer, the temperature variation betweenthe operation of the engine and non-operation of the same after stoppingis considerably large so that the gas pressure decreases at lowtemperature after the stopping of the engine so that a sufficient amountrequired for the starting may not be supplied. However, the pressure ofthe storage gas is not so lowered when the gas is stored at lowertemperature from the beginning by arranging the gas storage deviceseparately. Thirdly, the reformer can be made small and it can bearranged in the exhaust gas pipe so that it is possible that therecirculation efficiency of the heat of the exhaust gas can beincreased.

The necessary amount of the reformed gas required for one starting isvery small and it is about 1 l in an engine having displacement of 2 l.Therefore, if we intend to store 3 l of gas for considering some morespare amount, the size of the storage device filled with adosrbingmember may be in an order of about 40 mm in the diameter and 80 mm inthe length. The size of the reformer may be about 25 mm in the diameterand 60 mm in the length and it may easily be accommodated in the exhaustgas tube.

INDUSTRIAL APPLICABILITY

As has been explained in the foregoing, according to the presentinvention, there is no need to mount an auxiliary fuel for startingbesides the fuel alcohol and the reformed alcohol gas is excellent inthe combustion characteristics such as small ignition energy so thatstarting is very easy. Therefore the present invention contributes insaving the fuel petroleum resources.

We claim:
 1. In combination, an alcohol engine which operatesexclusively on alcohol fuel, a source of alcohol fuel connected to saidengine, and a starter for said engine, said starter comprising:meansconnected to said fuel source for receiving alcohol fuel from said fuelsource and reforming a portion of said alcohol fuel during operation ofsaid engine into gaseous fuel containing hydrogen and carbon monoxide asits main components, comprising reforming means for producing saidgaseous fuel, and storage means for storing said gaseous fuel, andwherein said reforming means is positioned to receive heat from anexhaust pipe, and said storage means is located in a position remotefrom said engine and said exhaust pipe so as not to be affected by heatfrom said engine or said exhaust pipe; and means for supplying saidgaseous fuel to said engine from said storage means only during startingperiods of said engine.
 2. The combination as set forth in claim 1,wherein said storage means contains an adsorbing material for adsorbingsaid gaseous fuel.
 3. The combination as set forth in claim 1, whereinsaid combination includes an engine starting switch, and said supplyingmeans is connected to said switch and responsive to actuation of saidswitch for supplying said gaseous fuel to said engine.
 4. Thecombination as set forth in claim 3, wherein said reforming means islocated within said exhaust pipe.
 5. A starter for an alcohol engineusing alcohol exclusively as its fuel, comprising in combination:anevaporator for evaporating said fuel alcohol into a gaseous phase; areformer for reforming the evaporated fuel alcohol into gaseous fuel,which fuel contains hydrogen and carbon monoxide, said reformercontaining a reforming catalyst as the main reforming element; anadsorbing member for storing the generated reformed gaseous fuel; and acontrol unit for controlling supply of the fuel alcohol into thereformer through the evaporator by detecting temperature and pressure ofthe gaseous fuel in the reformer and controlling feed of the reformedgaseous fuel.
 6. A starter for an alcohol engine as claimed in claim 5,wherein the evaporator and the reformer are built in a unitarycontainer.
 7. A starter for an alcohol engine as claimed in claim 5 or6, wherein the reformer contains said adsorbing member to act as astorage device for storing the reformed gaseous fuel.
 8. A starter foran alcohol engine as claimed in claim 5 and further including electricheating means for heating said catalyst, and wherein the control unitsupplies an electric current to said heating means to heat the catalystto make it active.